Reversing switch



March so, 1943. I H. M. EVJIEN 2314,2514

REVERSING SWITCH Filed Feb. 25, 1942 2 Sheets-Sheet 1 Q 25 26% F? C F [Emm 43 12 1 J4 INVENTOR.

Me A KON Mi Evurm Pren a Mar. 30.194:

of Delaware UNITED STATES" PATENT O C I l I navaa s g s wrrcu I I I Haakon M. Evjen, Houston, Ten, assignor to Nordel Corporation, Houston, Tex, a corporation Application February 25, 1942, Serial No. 432,11:

4 Claims. ((1200-23) This invention relates to reversing switchesand more particularly to a switch suited ioruse in geophysical exploration systems of the type shown in the application of Knute Evjen, Ser. No.

310,109 which embodies an earth current circuit including a current-source and a controlled reversingmesns for passing a current reversed at a predetermined controlled lowirequency through Fig. 5 is a plan view of still another embodi ment of the invention; and

the earth between spscedearth electrodes, and

afl-potential circuit potential pick-up electrodes located at spaced points adjacent the earth's surface and lying within the iield of influence of the earth current. The potential circuit is provided with a reversing switch synchronized with the firstreversing switch for converting the picked-up potential into a unidirectional potential suitable for actuating a direct current measuring instrument such as a galvanometer- The earth current circuit and the potential circuit are coupled by a coupling circuit which includes means for producing a potential drop proportionalto the total current now-.- ing in the earth current circuit and for balancing a controllable" portion of this potential drop in a system the type above indicated.

Fig. 6 is an end elevation thereof with parts broken away. 7

Referring first to Fig. .2, the switch is shown as comprising a pair of side. plates III which are mounted at their lower ends on blocks I! attached to a suitable base It. Either the plates III or the blocks i! or both may be made of insulating material. At their upper ends the plates in are attached to insulating blocks I which.

are secured together by a tie rod it. v

The plates ll carry flexible leaf spring members II which are mounted on bolts ll extending through said plates and secured by nuts 2.. The bolts II are provided with spacing sleeves 21 which secure the leaf springs it in position. The bolts it form binding posts for establishing electrical connections to the springs it. The side plates l8 may be made of conducting material with the sleeves 2! formed as bosses thereon or the plates 10 may be made of insulating material withthe electrical connection established by the are made 01' insulating material they may be 7 mounteddirectly on the base it as the additional insulation provided by the blocks II will not be required.

Another object is to provide a reversing switch having novel and improved adjusting mechanism of have been set forth for purposes oi illus tration.

In the drawings: Fig. 1 is a schematic view showing the reversing switch embodying the present invention as applied to the earth currentcircuit oi a geophysical exploration system 01 the type above referred to;

Fig. 2 is an enlarged detail "view of the rev'ersing switch;

Fig. 3.15 a. plan view of another. embodiment of the invention;

Fig. 4 is an endelevation thereoi;

The spring members il are provided with re-v versing contacts 2 2 to 25. The reversing member comprises a bar of insulating material mounted on a shaft 3i which is journalled in a bracket 32 having cars 33 secured tothe side plates ill by nuts 20. The insulating. bar 30 is provided at its ends with conducting members 35 and 38 respectively which form, ineiiect, mov-.

shaft 4| which is threaded in a bore 42 formed on the side plates l0 and is provided with a knurled adjusting nut 43. The stop means engage the ends of thespring members i8 to limit the movement of the respective contacts 22 to 25 in a closing direction while permitting. the spring members I! to be flexed outwardly with the bar t0 when the respective contacts are engaged b the conducting members 35 and 36.

rotating shaft 64 is connected through a gear train, enclosed within a housing 55, to the shaft I of an electric motor 51. The motor 51 is driven from mains 58 through a speed control device 8! and is provided with an indicator 80 to indicate the speed of operation thereof.

The earth current circuit'is shown as comprising a source 6| of direct current, such as a generator or battery, connected in series circuit with an ammeter 62, a resistance 3, representing a load, and feed lines 64 and 65. The lines N and II are connected respectively to the two bolts I! forming the binding posts for the stationary switch contacts. Lines 10 and H are connected by screws 31 and 38 to the contact members 3! and 36 respectively. The lines HI and H lead to suitable ground electrodes 12 and 13 respectively which are spaced a convenient distance apart and, when the reversing switch is operated in the manner to be described, pass through the earth circuit an alternating current having a frequency corresponding to the speed or operation of said switch. This current may be measured by the smmeter 62 and may be adjusted within desired limits by suitable regulation of the source H. The frequency of this earth current may be controlled by controlling the speed of the motor 51 by means of the regulator 69 and may be determined by the indicator 6!.

Operation of the motor 51 causes a corresponding rotational movement of the disc 83 and through the link 5|, a rocking movement of the shaft ll and of the contact bar 30 which is carried thereby. Rocking movement of the bar 80 in one direction causes the contacts 35 and 86 to engage contacts 25 and 23 and, in the other direction, causes contacts 35 and 36 to engage contacts 22 and 24, thereby reversing the connection between the lines 84 and N and the lines II and 1 i The timing of the closing and opening of the two sets of contacts may be adjusted by means of the adjustable stops Hi. The stops may be adjusted to provide gaps between the opening and closing of the two sets of contacts, or if desired an overlap may be provided by so adjusting the stops that the contacts 24 and 22, for example, close before the contacts 23 and 25 open. In the prospecting system shown in the Knute Evjen application above mentioned, for example, the reversing switch in the earth current circuit may be adjusted to have a predetermined gap between the opening and closing of the respective contacts and the reversing switch in the potential pick-up circuit may be adjusted to have an overlap so as to prevent fluctuation in the direct currentmeasuring instrument. Theoverlap may, for example, be of longer duration than the gap of-the switch in the earth current circuit.

The construction is such that a. plurality of similar reversing switches may be mounted on the same shaft 3i and may be actuated in unison with .the various contact members timed as desired by the adjustable stop members.

In the embodiment of Figs. 3 and 4 the shaft ii is shown as mounted in brackets 80 carried by a base 8i. The shaft 3! carries a pair of bars 82 01 insulating material on each of which is mounted a block 83. Each block 83 carries a leaf spring member 84 which may be attached by screws 85 and carries at its ends contact members 88. Brackets 81, attached to the bar 82 serve as stops to limit the forward movement of the leaf spring 84 and the contacts 86. Adjustable stationary contact members iii are mounted on rods II which are threaded into brackets .2 of conducting material, carried on uprights N of insulating material attached to the base ll. Thumb nuts 84 are provided for adjusting the position of the rods 8|. Lock nuts ll secure the rods Si in adjusted position.

The stationary contacts are cross connected as indicated by lines 86 and are thus connected in pairs to the lines 64 and I. The contact memhers I! are connected to lines Ill and II of Fig. 1.

In this embodiment the shaft II is rocked by the motor 51 as shown in Fig. 1 and cause; the contacts II to alternately make and break wiib the pairs of stationary contacts II on oppositr sides of the shaft ll, thereby reversing the connections from the lines 04 and OI to the lines Ill and 1|.

In Figs. 5 and 6 the invention is shown as applied to s pair or vacuum contact switches. In this embodiment a pair of vacuum switche I or standard type are shown as having iixed contact; Ill and a movable contact "2 carried on an arm III which -is pivoted to the base I and is actuated by a lever Ill. The switches are mounted on a bracket III which is secured to a base IN. A shaft ll" is mounted in brackets III attached to the base I01 and carries a pair of cross bars H0. Each bar I Hi is provided with end brackets H l in which adjustable threaded rods H2 are secured. A spring member Ill extends between the rods I I2 and is attached at its center to the lever I05. The tension of the spring member Ill may be adjusted as desired by means of thethreadedrodsll2. l

The stationary contacts ill of the two switches I" are cross connected as indicated by lines ill and are thus connected in pairs to lines Cl and II. The movable contacts are connected to lines II and H.

When the shaft 3 I is rocked the tension of the spring members ill actuates the levers III to cause the movable contacts "2 to engage alternately the fixed contact "I, therebyreversing the connections between the lines N and II and the lines It and II.

It is to be noted that all of the above described embodiments are self-centering; that is, mid

point between break and make is unaffected by ordinary wear and use. This is an important advantage when a plurality of such switches are mounted on the same shaft to be operated in synchronism as in the Evien system above referred to. A plurality of such switches may be adjusted to have different length gaps or overlaps at reversal as described while retaining accurate phas relationships since the various switches may be so set that the mid-points coincide regardless oi the mak and break timing.

Althoughcertain specific embodiments of the invention have been shown for purposes of illustration, it is to be understood that various changes may be made therein as will readily appear to a person skilled in the art. The invention is only to b limited in accordance with the scope of the following claims.

What is claimed is:

1. A switch comprising an arm having a contact member, a shaft carrying said arm, mechanism connected to rock said shaft at a controlled frequency, a pair of contacts positioned to be engaged respectively bysaid contact member when said arm rocks in opposite directions, spring means carrying said contacts and arranged to flex in response to the rocking movement of said am after the respective contacts have been closed, and stop means limiting the return movement of said contacts to thereby cause said contacts to break contact with said contact member at predetermined positions of said arm, said stop members being. adjustable for controlling the extent of gap or overlap at reversal.

2. A switch comprising an arm having a contact member providing contacts at opposite sides thereof, a shaft carrying said arm, mechanism connected to rock said shaft at a controlled fre quency, a leaf spring mounted on each side of said am and carryinga contact in a position to engage said first contact in response to rocking ='movement of said arm and being arranged to ile): in response to said rocking movement after the respective contacts have been closed, and stop means limiting the return movement of said leaf spring, to thereby ,cause said contacts to break contact with said contact member in predetermined positions of said arm, said stop members being adjustable for controlling the extent of gap or overlap at reversal.

3. A switch comprising a shaft, mechanism connected to rock said shaft at a controlled frequency, movable switch contacts, an actuating member therefor, a bracket carried by said shaft to rock therewith, a spring member having its ends secured to said bracket and having an intermediate portion secured to said actuating mem her to actuate the same as the shaft rocks in opposite directions, and means adjusting th tension of said spring member and the position of said intermediate portion for controlling the make and break timing of said contacts.

4. A reversing switch comprising a shaft,

mechanism to rock said shaft from side to side at 

